Comparison of the rheology of bubbly liquids prepared by whisking air into a viscous liquid (honey) and a shear-thinning liquid (guar gum solutions)

Combining fracture mechanics and rheology to investigate the impact of micro-aeration on chocolate oral processing

This study presents a rigorous mechanical characterisation investigation on milk chocolate with varying porosities, at different temperatures and strain rate levels. Uniaxial compression tests at temperatures varying from 20 °C to 30 °C were performed to measure the bulk properties of chocolate as a function of porosity and temperature. Fracture experiments were also conducted to compute the fracture energy at temperature levels between 20 °C and 30 °C for all tested samples. Additionally, rheological experiments are conducted to compute the viscosity of the different chocolates at 37 °C. This combined experimental analysis of solid mechanics, fracture mechanics, and rheology aims to define the impact of temperature and chocolate's phase change from solid to liquid on its mechanical properties. Moreover, the impact of micro-aeration on the relationship between material properties and temperature is discussed. The results demonstrate a significant impact of both temperature and micro-aeration on the chocolate's material properties; fracture stresses decrease with micro-aeration due to the presence of micro-pores creating weak links in the chocolate matrix, the critical strain energy release rate decreases with micro-aeration at temperatures up to 25 °C and increases at temperatures above 30 °C. Finally, the viscosity at 37 °C increases with increasing porosity due to the obstruction of the flow by micro-pores acting as "solid" particles. The results highlight how the impact of micro-aeration on the material properties of chocolate alters as the testing temperature rises and the material changes phase. The relationships between the micro-aeration and material properties and the dependence of temperature on the different mechanical properties are used to explain the difference in textural attributes as obtained from temporal dominance sensation tests. This study seeks to contribute valuable insights into the field of chocolate technology, emphasizing the need for a combined engineering approach to understand the structural breakdown of chocolate during oral processing as mechanisms such as chewing, melting, mixing and shearing occur.

Microbubbles in Food Technology

Microbubbles are largely unused in the food industry yet have promising capabilities as environmentally friendly cleaning and supporting agents within products and production lines due to their unique physical behaviors. Their small diameters increase their dispersion throughout liquid materials, promote reactivity because of their high specific surface area, enhance dissolution of gases into the surrounding liquid phase, and promote the generation of reactive chemical species. This article reviews techniques to generate microbubbles, their modes of action to enhance cleaning and disinfection, their contributions to functional and mechanical properties of food materials, and their use in supporting the growth of living organisms in hydroponics or bioreactors. The utility and diverse applications of microbubbles, combined with their low intrinsic ingredient cost, strongly encourage their increased adoption within the food industry in coming years.

Effect of Shear-Thinning Property on the Energy Performance and Flow Field of an Axial Flow Pump

In the chemical and petroleum industry, the axial flow pump is widely used for the circulation pipeline system, and most of the transportation mediums are the shear-thinning non-Newtonian fluids. However, previous investigations on axial flow pumps are focused on water, which leads to a considerable deviation between the actual application and the research finding. In this work, shear-thinning non-Newtonian fluid (CMC solution) and viscous Newtonian fluid (the viscosity equals the apparent viscosity of CMC solution as the flow index is 1) are selected as the working medium. Based on the research output, lower apparent viscosity occurs in the near-wall and rotor–stator interaction region due to the larger velocity gradient. The shear-thinning property results in an increased tip leakage flow rate, and a sharp decline in friction loss. Compared to the viscous Newtonian fluid, the head and efficiency of the pump improves substantially for the shear-thinning fluid. The discrepancy is observed to increase with a higher flow rate. The comprehensive analysis of flow field and energy performance reveals that friction loss is still the main part of the total loss in the shear-thinning fluid.

Effect of egg freshness on texture and baking characteristics of batter systems formulated using egg, flour and sugar

BACKGROUND

The aim of this work was to evaluate the effects of egg freshness on baking properties and final qualities in batter systems. Batters were made with eggs of different freshness, and the properties of batter systems were studied through rheological analysis, rapid viscosity analysis (RVA), differential scanning calorimetry (DSC), batter density and expansion rate during the baking and cooling processes. Moreover, the qualities of final baked systems were investigated, including specific volume and texture profile analysis (TPA).

RESULTS

The flow behavior of batters showed that the consistency index (K) decreased as the Haugh unit (HU) value decreased, while the flow behavior index (n) increased. Both the storage modulus (G') and loss modulus (G″) determined by mechanical spectra at 20 °C decreased with decreasing HU. RVA and DSC determinations revealed that lower-HU samples had a lower viscosity in the baking process and a shorter time for starch gelatinization and egg protein denaturation. Observation of the batter density revealed an increasing change, which was reflected by a decrease in the specific volume of final models. TPA showed significant differences in hardness and chewiness, but no significant differences in springiness and cohesiveness were found.

CONCLUSION

The egg freshness affected the properties of batter systems.